FIG. 11 shows a conventional rubber crawler track C. Steel cords S are embedded in a rubber crawler body shaped as an endless belt from a rubber elastic body as circumferential reinforcing members, and metallic cores M are embedded therein as width directional reinforcing members. K is a guide protrusion for guiding a rolling wheel.
In the conventional rubber crawler track, as shown in FIG. 12A, side displacement occurs between adjacent metal cores. Because of the side displacement, a rolling wheel R of a crawler traveling device goes across the guide protrusion K to run off, and the rubber crawler track comes off the traveling device.
In addition, the conventional rubber crawler track is so constructed, as shown in FIG. 12B, that the rolling wheel R rolls on the guide protrusions K. Therefore, the rolling wheel R rolls on the guide protrusions K, sinking between the metal cores adjoining longitudinally in a circumferential direction and thereby increasing traveling vibration. To solve this problem, a rubber crawler track for reducing the sinking of the rolling wheel has been proposed. Therein, the rolling face of the guide protrusion is extended circumferentially, the guide protrusion is T-shaped, and the distance between the metal cores is shortened. However, as to even this structure, the metal cores incline and the rolling wheels sink after all.
An invention disclosed in Japanese utility model registration No. 2551937 has been proposed to prevent wheel run-off caused by the side displacement of the rolling wheel. The invention is to prevent the side displacement of the rubber crawler track and the wheel run-off by arranging horizontal protrusions MP on a metal core M. In FIG. 13A, MY is a metal core wing portion.
In addition, an invention disclosed in Japanese patent No. 2554552 and Japanese utility model publication No. 000226 of 1996 has been proposed to prevent traveling vibration due to the sinking of the rolling wheel and the inclination of the metal cores. In this invention, the top of the guide protrusion K forms an inclination KT to form a continuous rolling wheel track and reduce the vibration. That is, when the rolling wheel R gets on guide protrusion overhangs KP, the overhangs KP gravitate somewhat to keep the height of track of the rolling wheel and approach the guide protrusion K of the adjacent metal core M to reduce the distance between the metal cores. In FIG. 14, MK is an engaging portion of the metal core.
Moreover, an invention disclosed in Japanese utility model registration No. 2601638 has been proposed to settle the following problems. Problem 1:
When the rolling wheel travels on the guide protrusions of the rubber crawler track, an external force such as a rolling wheel load is added on crawler circumferential ends of the guide protrusion top. According to this, the guide protrusion inclines, the rolling wheel sinks, and the traveling vibration occurs.
Problem 2:
The metal core comes off the rubber crawler track in a stroke due to an external force like a pushing-up from the side of the guide protrusion, caused by the interaction between the crawler track and the traveling device. Here, the interaction is caused by stones pushing between the guide protrusions or by the discrepancy of the traveling device. In this case, sometimes, adhesion between the rubber and the metal core is overcome, and core is peeled away.
In the invention of Japanese utility model registration No. 2601638, the horizontal protrusions MP are formed within the thickness of the wing portion of the metal core embedded in the rubber crawler track or below it so as to cross perpendicularly to the side of the metal core. When the metal core is embedded in the rubber crawler body, horizontal protrusions MP between the adjacent metal cores are embedded so as to overlap in a crawler width direction (lateral direction) and in a crawler thickness direction (vertical direction). Therefore, a local side displacement of the rubber crawler track and vibration of the metal core are prevented, thereby preventing the crawler run-off, the rolling wheel sinking, and the metal core peel-off (See FIG. 13B). Reference is made to                Japanese utility model registration No. 2551937,        Japanese utility model registration No. 2601638,        Japanese patent No. 2554552, and        Japanese utility model publication No. 000226 of 1996.        